The Midwest state of Iowa has scheduled its presidential caucus vote for January 3, in what amounts to the official start of the process to choose a Republican Party nominee to run against President Barack Obama next year.

The battle for the party nomination has taken a personal turn in recent days between two of the top contenders, former Massachusetts Governor Mitt Romney and Texas Governor Rick Perry.

Tensions between the Romney and Perry camps have been building for months and their apparent mutual dislike for each other burst onto the stage during the most recent Republican debate in Las Vegas, Nevada.

Perry came into the debate determined to be more aggressive after several mediocre performances and a drop in support in public opinion polls.

Perry chose to focus on allegations several years old that Romney knowingly employed illegal immigrants to cut his lawn.

PERRY: “And Mitt, you lose all of your standing from my perspective because you hired illegals [illegal workers].”

ROMNEY: “I don’t think I’ve ever hired an illegal in my life.

PERRY: "I'll tell you what the facts are!"

ROMNEY: "Rick, again, I'm speaking! I'm speaking!”

Romney says he stopped using the landscaping company once he found they used illegal workers.

But he and Perry continued to spar over the issue during the debate. At one point a clearly frustrated Romney gently put his hand on Perry’s shoulder in an effort to get him to stop talking.

“You have a problem with allowing someone to finish speaking and I suggest that if you want to become president of the United States you have to let both people speak.”

Illegal immigration has become an issue in the Republican campaign and Perry has been criticized by some of his rivals for not doing more to stop illegal immigrants from coming into Texas.

Public opinion polls show Romney and Georgia businessman Herman Cain are the top two contenders for the Republican nomination at the moment. Perry trails further behind along with Texas Congressman Ron Paul, former U.S. House speaker Newt Gingrich and Minnesota Congresswoman Michele Bachmann.

Rounding out the Republican field are former Pennsylvania Senator Rick Santorum and former Utah Governor Jon Huntsman.

The surprise of late has been political newcomer Herman Cain, the former top executive of a pizza company and the only African-American in the field.

Cain has gained notice with an appealing personality and a bold tax reform plan.

But Cain spent most of the latest debate trying to fend off attacks from rivals that his tax plan would wind up hurting poor and middle class voters.

“Politicians, they don’t want to throw out the current tax code and put in something that is simple and fair,” he said.

Analysts say Cain has risen in the polls because conservative Republican voters are still looking for an alternative to Mitt Romney.

Tom DeFrank is Washington bureau chief for the New York Daily News and a regular analyst on VOA’s Issues in the News program.

“He is a personification of a protest by the most conservative elements of the Republican party, who need a standard-bearer because they don’t like Mitt Romney who has emerged as the frontrunner but one who is viewed with a lack of enthusiasm by especially the Tea Party activists and the evangelicals [Christians],” he said.

Perry is now trying to regain his footing and offer a stronger challenge to Romney, but political strategist Matthew Dowd, an analyst for ABC News, says the tensions between the two men could turn off voters.

“It does not help the Republicans to have this kind of fight, especially how personal it got. That helps Obama. But President Obama is in a difficult spot and he knows it because of the state of the economy,” said Dowd.

White House officials have focused most of their attention on Romney of late, signaling that they believe the former Massachusetts governor remains the most likely Republican nominee to face President Obama next year.